GO to your local greenhouse / plant stand. Do not go to Home Depot or Lowes...go to a real nursery.

Most nurseries start their pants in the perfect medium....just ask what they use.

I found a nursery that uses PRO MIX...so far so good.

Real light, airy and spongy.

PH 6.5

Any nursery that grows their own plants have something that will work.

Good luck!